Conventional cattle feeds such as corn and alfalfa often fail to provide sufficient energy for cattle, especially lactating dairy cattle during periods of heavy milk production. Feed containing a high proportion of corn also has a tendency to depress the milk fat content of the milk produced by such cattle. Fat is a concentrated energy source, and it is known that if the proportion of fat in cattle feed is increased, lactating dairy cattle produce high milk yields without draining their reserves of body fat and without diminishing the proportion of milk fat in the milk produced.
However, it has been found that if the proportion of fat in the diet of cattle exceeds about 5% of the total feed solids, the feed has toxic effects upon the microorganisms in the rumen of the cattle. It appears that fat reduces the growth rate or even kills certain microorganisms which digest fiber in the cow's rumen, thereby lowering fiber digestibility. This deleterious effect on the cow's rumen is particularly true of unsaturated fats. Although the decreased fiber digestion in the rumen is partially compensated by greater fiber digestion in the lower parts of the alimentary canal, the total energy derived is less than that resulting from more complete microbial digestion in the rumen.
There has been a continuing need for new dietary supplements for animal feed which can be fed to ruminant animals without interfering with the rumen microorganisms, or being rendered ineffective by the rumen microorganisms.
U.S. Pat. Nos. 4,642,317; 4,826,694; 4,853,233; and 4,909,138 describe the incorporation of insoluble fatty acid salts in ruminant feed as a means of increasing the fat content of the feed without deleteriously affecting the ruminant digestion cycle. A feed additive such as fatty acid calcium salt functions as a rumen inert product which passes through the rumen without interfering with rumen fermentation (i.e., a rumen bypass product), and is subsequently metabolized in the abomasum or small intestine of the ruminant.
Another important aspect of lactating dairy cattle feed relates to periods of negative energy balance in which animal body mass is metabolized to compensate for the energy deficiency. If a consequential metabolic ketosis disorder occurs in the lactating animals, a reduced yield of milk occurs.
Glucose is an important nutrient and energy source for lactating ruminants. Bloodglucose is the main precursor for lactose. A lactating cow that produces 30 kg of milk per day utilizes more than 2 kg of glucose daily.
If glucose is administered to lactating ruminants in feedstuff, it is converted to lower fatty acids in the rumen, and little or no glucose is available for absorption in the lower digestive tract. The glucose deficit in lactating ruminants is satisfied mainly by gluconeogenesis, i.e., by the metabolic formation of glucose from glucogenous compounds such as propionate. The availability of glucogenous compounds in highly lactating ruminants is an important feed nutrition factor.
Accordingly, it is an object of the invention to provide a fatty acid salt composition which can function as a rumen bypass animal feed supplement, and permit a beneficial increase in the dietary fat content of the feed.
It is another object of this invention to provide a process for preparing a fatty acid salt ruminant feed supplement having a content of propionate glucogenous ingredient which has rumen bypass protection.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.